Results of linear stability analysis (LSI) of the Rayleigh-Taylor instability for various setups. Models generally increase in complexity from top to bottom. Wavelength is scaled by layer thickness (b) or viscosity decay length (L). Rheology is the  power law type with exponent n>1 or Newtonian when n=1.  Methods for solving for the wavelength are analytical linear stability analysis (LS) or numerical techniques (num).